Emdash source with visual editor image upload fix

Fixes:
1. media.ts: wrap placeholder generation in try-catch
2. toolbar.ts: check r.ok, display error message in popover

scripts/build-perf-d1.mjs

@@ -0,0 +1,16 @@
+#!/usr/bin/env node
+import { spawnSync } from "node:child_process";
+import { writeFileSync } from "node:fs";
+import { dirname, resolve } from "node:path";
+import { fileURLToPath } from "node:url";
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+const fixtureDir = resolve(__dirname, "..", "fixtures/perf-site");
+
+const r = spawnSync("pnpm", ["exec", "astro", "build"], {
+	cwd: fixtureDir,
+	stdio: "inherit",
+	env: { ...process.env, EMDASH_FIXTURE_TARGET: "d1" },
+});
+if (r.status !== 0) process.exit(r.status ?? 1);
+writeFileSync(resolve(fixtureDir, "dist/.perf-target"), "d1\n");